Whatipū is the most southerly of the Auckland, Waitākere Ranges west coast beaches, on the northern side of the Manukau Heads. The beach itself is generally considered to be a relatively small crescent with Paratutae Island at the south eastern end. But it in fact is the edge of the extensive sand banks that run all the way up to Karekare, a tough half day of coastal hiking.
There is also a sea cave, now a long way from the actual coast. You can visit by following a short trail along the edge of the sand dunes and cliff to the north. Or you can hike to a viewpoint above the beach, with access on the south side of the carpark. The latter is part of the amazing Omamawanui Track.
You may also notice Cutter Rock, once a popular abseiling spot until a large part of it collapsed.
You will need a vehicle or a ride to get to Whatipū, though there is a lodge and camping near the beach. It takes about 45 minutes from the central city to drive there via Cornwallis and Huia. The last section of the road is narrow and winding with a metal surface. This probably does help keep the numbers down a bit.